A study of mutual coupling effects on the direction finding performance of ESPRIT with a linear microstrip patch array using the method of moments

There has been a rapid growth of wireless communication systems. One promising approach to increase spectral efficiency, and thus also increasing capacity, is to use antenna arrays at the cell sites. Array processing techniques can then be used to receive and transmit multiple signals that are separated in space. One of the array processing techniques for determining the directions of arrival (DOAs) of the signals in the uplink is ESPRIT. The essence of ESPRIT is that we can divide the antenna into two or more identical subarrays. Due to mutual coupling between the elements in the array we know that the element patterns are perturbed and the subarrays will no longer be identical. In this paper we discuss what kind of errors that mutual coupling introduces to the accuracy of the ESPRIT-algorithm. First, we generate element patterns for a 12-element linear microstrip patch array using a rigorous moment method algorithm. Next we apply ESPRIT for different scenarios and study the direction of arrival-estimates. We also investigate the concept of using dummy elements to improve the identical subarray approximation.